As is known in the art, chewing gum compositions typically comprise a water soluble bulk portion, a water insoluble chewing gum base portion and typically water insoluble flavoring agents. The water soluble portion dissipates with a portion of the flavoring agent over a period of time during chewing. The gum base portion is retained in the mouth throughout the chewing process.
The gum base includes a number of ingredients, some of which are subject to deterioration through oxidation during storage. The insoluble gum base generally comprises elastomers, elastomer plasticizers, waxes, fats, oils, softeners, emulsifiers, fillers, texturizers and miscellaneous ingredients such as antioxidants, preservatives, colorants and whiteners. Ingredients having a double bond between carbon atoms, including fats, oils, some elastomers and elastomer plasticizers, are susceptible to oxidation. The gum base constitutes between 5-95% by weight of the chewing gum composition, more typically 10-50% by weight of the chewing gum, and most commonly 15-25% by weight of the chewing gum.
Commonly used natural or artificial antioxidants/preservatives include beta-carotenes, acidulants (e.g. Vitamin C), propyl gallate, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary butyl hydroquinone (TBHQ). The most notable and commonly used of these include synthetic antioxidants BHA, BHT and TBHQ.
Tocopherols are naturally occurring compounds which are known to have antioxidant properties. The most common tocopherol, alpha-tocopherol, is also known as vitamin E. The other common homologs are beta, gamma and delta tocopherols. All of these tocopherol homologs are FDA approved additives which have been shown to be safe in animal testing. Natural tocopherols are usually derived from vegetable oils, especially soybean oil. Tocopherols can also be found in many spices, fruits, nuts, seeds and other plant sources.
Unfortunately, the tocopherol homologs have been found to be generally less effective than BHA and BHT in preventing oxidation of chewing gum base components. Tocopherols also have upper usage level limits, above which oxidation of the gum base ingredients will start to increase again. Tocopherols have been used successfully as stabilizers for some chewing gum ingredients, such as styrene butadiene rubber, when added in combination with certain synthetic stabilizers. U.S. Pat. No. 4,489,099 issued to Shaheen et al. discloses the use of vitamin E tocopherol in combination with dilauryl thiodipropionate (DLTDP). However, it has previously been less effective to use tocopherols in chewing gum base compositions, by themselves.